Catalytic reforming of naphtha is widely used in the petroleum refining industry to increase the octane of naphtha for gasoline blending. Important reactions that occur in catalytic reforming include 1) the dehydrogenation of naphthenes to aromatics, 2) isomerization of paraffins to isoparaffins, and 3) the dehydrocyclization of paraffins to aromatics.
Undesirable reactions include the hydrocracking of paraffins and naphthenes and the dealkylation of aromatics that results in the loss of liquid and hydrogen yields and the production of lower-valued fuel gas. A more selective reforming catalyst could significantly increase reforming margins by increasing liquid and hydrogen yields via reduced hydrocracking and increased paraffin dehydrocyclization activity.
Dual functional reforming catalysts have been commercialized. Early reforming catalysts consisted of platinum metal supported on an acidic, chlorided alumina. Chlorine is typically added to the reforming catalyst to maintain the acidity. The chlorine needs to be replenished and presents operating issues. Chlorine is corrosive to the unit and highly reactive. Their key limitation was coke stability. Bimetallic reforming catalysts (PtRe/Al2O3) have been introduced with improved stability and provided equivalent activity and selectivity to earlier catalysts. PtIr/Al2O3 catalysts have also been commercialized that are higher activity but less selective than Pt and PtRe catalysts. Other reforming catalyst, such as PtSn, seek to provide higher stability for improved operation at lower pressure. However, there remains a need for reforming catalyst with improved selectivity and/or that provide an increase in gasoline yield.